In fact, it has been engineered that way. Bernanke has been explicitly targeting equities, hoping to trigger a beneficent spiral that he calls“the wealth effect”- stock prices go up, people feel richer and spend, and the economy recovers. But with fundamentals still depressed, this boom cannot be sustained.

There are many events and eventualities under which throwing more money at the market will make no difference. Central banks cannot reverse a war, or a negative trade shock, or a negative production shock, or a negative energy shock simply by throwing money at it. And there are severe limits to their power to counteract financial contractions outside their jurisdiction (although in all fairness the Federal Reserve has expanded these limits in extending liquidity lines to foreign banks). Sooner or later the engineered recovery will be broken by an event outside the control of central bankers and politicians. In creating a false stability, the Federal Reserve has actually destabilised the economy, by distorting investors’ perceptions.

But, of course, some analysts think that this time really is different. Here’s a chartfrom Goldmanshowing the S&P500 by sectoral composition:

The implication here is clear - with no obvious sectoral bulge like that of the late 1970s, the tech bubble, and the financial bubble - there is no bubble. But what if the bubble is spread evenly over multiple sectors? After all, the Federal Reserve has been reinflating Wall Street in general rather than any one sector in particular.

Is this the final blowout top? I’m not sure. But I would be shocked to see this bubble live beyond 2013, or 2014 at the latest. I don’t know which straw will break the illusion. Middle eastern war? Hostility between China and Japan? North Korea? Chinese real estate and subprime meltdown? Student debt? Eurozone? Natural disasters? Who knows...

The wider implications may not be as bad as 2008. The debt bubble has already burst, and the deleveraging cycle has already begun. Total debt is slowly shrinking.It is plausible that we will only see a steep correction in stocks, rather than some kind of wider economic calamity. On the other hand, it is also plausible that this bursting bubble may herald a deeper, darker new phase of the depression.

Lance Roberts is the General Partner and Chief Portfolio Strategist for STA Wealth Management. He is also the host of "Street Talk with Lance Roberts", Chief Editor of "The X-Factor" Investment Newsletter and the Streettalklive daily blog. Follow Lance on Facebook, Twitter and Linked-In